1. Field of the Invention
The present invention relates to an air intake apparatus of an engine, in particular, of an internal combustion engine.
2. Description of Related Art
Hitherto, as an air intake apparatus of an engine, in particular, of an internal combustion engine, the air intake apparatus is known which includes an intake duct connected to an air cleaner, a surge tank connected to a downstream portion of the intake duct, and a plurality of intake branch pipes connecting the surge tank and the engine. The air intake apparatus is further provided with an intake air control valve in a dividing portion which divides the surge tank into a first surge tank and a second surge tank, and is formed so that resulting from the full opening of the intake air control valve, the first surge tank and the second surge tank are communicated with each other and resulting from the full closing thereof, the communication between the first surge tank and the second surge tank is shut off.
In addition, in the above-described apparatus, by controlling the intake air control valve so as to open and close the valve depending on the driving states of the engine, that is, by closing the valve when the engine drives in the state of high load and low speed rotation, and by opening the valve when the engine drives in the state of high load and high speed rotation, an equivalent pipe length of an air intake passage is changed so that a high charging efficiency can be ensured over a whole range of revolution speed of the engine by utilizing an inertia effect of an intake air.
As to such an air intake apparatus of the internal combustion engine as described above, the structure shown in FIG. 5 is conventionally known. (Refer to JP-A-9-125970.)
In the air intake apparatus shown in FIG. 5, a surge tank portion includes a surge tank 103 having a receiving portion 102 for receiving an outside surface of an intake air control valve 101 of which the open and close operation is controlled depending on the states of the engine and having inside a shape corresponding to that of the intake air control valve 101, and is provided with a first divided body (lower piece) 104 made of resin which includes an entire body of the receiving portion 102 and has a part of the surge tank 103 integrally, and a second divided body (upper piece) 105 made of resin which has a remaining part of the surge tank 103 integrally and bonded to the first divided body 104 by means of a method of vibration adhesion. The receiving portion 102 has an outer surface continuing a divided line between the first and second divided bodies 104 and 105, and the second divided body 105 integrally includes an inner wall in a shape corresponding to that of the outside surface of the receiving portion 102, and by bonding the first and second divided bodies 104 and 105 to each other on respective adhesion surfaces 106 and 107 by means of the method of the vibration adhesion, an inner wall in the second divided body 105 is simultaneously bonded to the outside surface of the receiving portion 102 by the vibration adhesion.
Further, the intake air control valve 101 is constituted so as to be arranged in the receiving portion 102 through an inserting hole 108 formed in the first divided body 104, and the intake air control valve 101 comprises a holder 110, a rotation shaft 111, a butterfly valve body 112 and a flange portion 113, and the flange portion 113 is fixedly secured to the first divided body 104 with bolts 114. Furthermore, a seal ring 115 is disposed on an outer periphery of the holder 110.
In the above conventional structure, when the first divided body 104 and the second divided body 105 are bonded to each other by means of the vibration adhesion, since the rigidity of the receiving portion 102 is low, there is a fear of causing deformation of the receiving portion 102 due to the vibration, and thereby, there is a fear of causing insufficient vibration adhesion of the receiving portion 102 to the second divided body 105.
Additionally, since the air intake apparatus has a structure in which the holder 110 assembled with the intake air control valve 101 is inserted through an insertion hole 108 formed in the first divided body 104 and is arranged in the receiving portion 102, there are caused problems that a seal between the holder 110 and the receiving portion 102 requires a high precision, and moreover a sealing property between the holder 110 and the receiving portion 102 is lowered by a permanent set in fatigue of a seal ring 115 caused due to aging deterioration.